A valve timing controller changes the relative rotational phase between a first rotary body rotating in synchronization with a crankshaft and a second rotary body rotating in synchronization with a camshaft to adjust valve timing. For example, JP-2005-98142A (U.S. Pat. No. 6,920,855B2) discloses a valve timing controller that increases and utilizes control torque generated by an electric motor so as to change a relative rotational phase between two rotary bodies. In this valve timing controller, by utilizing large control torque outputted from a planetary gear mechanism, a response to a change in a relative rotational phase and an adjustment response of the valve timing can be enhanced.
In the valve timing controller disclosed in JP-2005-98142A, a planetary gear mechanism is accommodated in the rotary body rotating in synchronization with the crankshaft. A planetary gear constructing the planetary gear mechanism is brought into close contact with the rotary body rotating in synchronization with the crankshaft and a transmission rotary body constructing the planetary gear mechanism. This restricts a shift of the planetary gear and the transmission rotary body in an axial direction, and restricts the malfunction of the planetary gear mechanism.
However, when the planetary gear of the planetary gear mechanism is brought into close contact with the rotary body moving in synchronization with the crankshaft or the transmission rotary body of the planetary gear mechanism, wear is caused by the relative sliding between elements brought into close contact with each other. To reduce this wear, supplying lubricating fluid into the rotary body moving in synchronization with the crankshaft can be considered. However, the lubricating fluid is increased in viscosity at the time of low temperature and hence the lubricating fluid flowing between the elements and having high viscosity produces a large sliding resistance. The large sliding resistance produced in this manner might cause the malfunction of the planetary gear mechanism, which is not desirable.